Does fracking cause earthquakes in BC?
Updated: Nov 19, 2022
The CBC recently published an article on two large, fracking-induced earthquakes near Ft. St. John, BC. One was magnitude 4.6 and the other magnitude 4.7, and these are strong enough to shake your house and the belongings in it. I am asked regularly about the dangers of fracking, and these events are a good reason to discuss the positives and negatives of fracking for British Columbia.
That is a good question. Oil and gas (hydrocarbons) are produced from tiny pore spaces, or holes, that exist between grains of sand and mud that make up sandstone and mudstone. At 2 km depth or more, if there is enough connection between the holes in the sandstone or mudstone, then hydrocarbons flow through the rock towards the vertical wells drilled to produce them. In rocks where the holes in the rock are not connected, companies need to drill wells horizontally and then frack the wells multiple times (known as multi-stage fracking) to produce the hydrocarbons. Think of the rock with unconnected holes as being a bit like a cement sidewalk - they are extracting hydrocarbons from that. Check out the video below on how multi-stage fracking works most of the time. The photos below the video show the types of rock and size of the holes that store the hydrocarbons accessed through multi-stage fracking.
Benefits of fracking
The benefits of fracking for BC are in employment, energy security, and government revenue. Since 2007, northeast BC has been a hotbed of horizontal drilling and multi-stage fracking. Hydrocarbons produced using these technologies dominate production in BC (see graphs below). The BC government takes a 5% royalty from each well drilled for the first 12 months, and then applies a royalty rate between 5 and 40%, based on the value of the hydrocarbons produced (e.g., price of natural gas versus oil). They also receive income tax from producers, companies, and individuals who work in or for the petroleum industry, and this results in billions of dollars in revenue for the BC government. Jobs in the petroleum industry are also well-paying, and gas produced in northeast BC is the main natural gas supply for residents of the Lower Mainland BC and for much of Washington State, USA.
Dangers of fracking
While there are benefits to fracking, there are also some serious drawbacks. First amongst these is induced seismicity or man-made earthquakes. When companies fracture the rock, they do so with pressurized fluid. If that fluid enters an existing fault or crack in the rock, it lubricates the rock and props open the crack allowing the rock to move. This produces an earthquake.
Most multi-stage fracking activity does not induce earthquakes, but greater than 2.5% do and that is a problem. Most induced earthquakes are small (less than magnitude 3.0; 3), but when they exceed magnitude 4, it is worrying (see graphs below). Government scientists have identified areas of higher risk for inducing earthquakes, but so far little has been acted upon. I expect we will continue to hear about these events in the news until the government develops guidelines and enforces rules. In the meantime, let's hope no one is hurt from one of these events.
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1) Nadaraju, G. and Elliot, D. 2010. Understanding Montney reservoir heterogeneity: A
geo-engineering approach. Encana Corporation.
2) Bai, B., Elgmati, M., Zhang, H., and Wei, M., 2013, Rock characterization of Fayetteville shale gas plays: Fuel, v. 105, p. 645-652.
3) BC Oil and Gas Commision. 2014. Investigation of Observed Seismicity in the Montney Trend. 32 p.
4) BC Oil and Gas Commission. 2012. Investigation of Induced Seismicity in the Horn River Basin. 29 p.